Compound for bleaching and preserving wood



UNITED STATES PATENT @rrrcm SAMUEL OABOT, OF BROOKLINE, MASSACHUSETTS.

COMPOUND FOR BLEACHING AND PRESERVING WOOD.

SPECIFICATION forming part of Letters Patent No. 515,191, dated February20, 1894.

Application filed \Tune 6, 1893. Serial No. 476,722. (No specimens.)

To alZZ whom it may concern.-

Be it known that I, SAMUEL CABOT, a citizen of the United States, and aresident of Brookline,in the county of Norfolk and State ofMassachusetts, have invented an Improvement in Compounds for Bleachingand Preserving Wood Surfaces, of which the following is a specification.

This invention is related to many others designed to improve or modifythe appearance of wood, or wood structures, by treating the same in manydifferent ways. It is especially intended for bleaching and preservingarchitectural erections and ornament thereon, in a peculiar andbeautiful manner; and it is well adapted for newly shingled roofs,which, by this means may be brought into harmony with the rest of thebuilding.

It is well known that the exposed surfaces of woods that are able toresist decay, become bleached or grayed by the action of the'elements,and that the action is vastly greater and more perfect on the sea coastthan elsewhere. This very marked difference seems to be due to thepresence of salt spray or foam taken up by the winds and often carriedfor long distances in the air, an opinion which is justified by the veryperfect bleaching of drift wood found upon the beach itself. Thisspontaneous bleaching of wood can only take place completely when aclean surface has been exposed, and when the wood is of such a kind asto withstand destructive decay, the time required for the completion ofthe natural process at the seashore being long, extending indeed overmany years. The result so obtained is very beautiful, the surface of thewood being uniformly covered by a soft silvery white or gray color,which harmonizes well with all the stained and other tints used inartistic architecture.

My invention is designed to produce by chemical treatment in allsuburban or country places, a like or superior result in a relativelyrapid and much more reliable manner, but one which extends neverthelessover a long period as compared with ordinary bleaching operations in thearts. To accomplish this I apply to the exposed surface of the wood apreparation consisting of water fifty parts, creosote oil seventy parts,chloride of lime ten parts; which being mixed together give rise to acreamy liquid in which the oily matter remains suspended or emulsified,a state of things largely due. to the alkaline character of the chlorideof lime, which always has an excess of caustic lime, and only a weakacid in combination; This preparation, or paint, as it may be regarded,is applied to the surface of the wood in sufficient quantities bya brushor otherwise. The coating is preferably made to freshly exposedsurfaces, in which case bleaching and preservative changes hegin atonce; but it is only by exposure to the elements conjoined with theapplied coating, and then after several months of such combined actionthat the most perfect results are obtained. These consist in the gradualbut thorough destruction of the glutinous and extractive matter betweenthe surface fibers and to an appreciable depth, as well as of theorganic coloring matter present of whatever kind, so that in the endpure cellulose alone is left visible upon the surface of the wood in agray-White silky condition liable to no further change.

As stated, I have discovered that the method or process of coating woodwith a paint substantially of the composition herein given, andconjointly exposing the coated wood to external atmospheric influences,yields excellent resnlts; better in quality'and more rapid than can beobtained by any other means known to me, and much better than can be gotby using either the chemical or the atmospheric influences alone. Fullexplanation of this fact is difficult, the bleaching action of thesunlight, ozone, and the moisture furnished by rain and dew, seems to beheightened by that of the hypochlorous acid or chlorine set free;butindependently of any such theory it may be assumed with strongprobability, that a Very slow decomposition of the large excessofchlorinated lime present, is effected by the carbonic acid of theatmosphere. In addition to this the preservative action of the creosoteoil, while it gives lasting qualities to inferior woods and lengthensthe duration of all,has apparently a specific influence in restrainingthe rotting tendencies of the surface and the extension of the same tothe cellulose; in which direction the salt of sea water is also active,though in a much less degree. The carbonate of and during that time thesurface'undergoing treatment is more or less disfigured by reason of thepartial and splotchy removal of color and of the resulting products andresidues generally. To remedy this'I add to the mixture alreadydescribed, two other substances,- namely zinc white thirty parts, andlinseed oil fifteen parts, and stir both into the emulsion consisting ofthe quantities of water, chlorinated lime, and creosote given above.These additions do not interfere with the working qualities, or with thebleaching and preservative properties of the resulting composition, onthe contrary, a heavy coating adheres more tenaciously to the wood andremains advantageously in contact with it pending the completion of theprocess; but the important effect obtained is an immediate simulation ofthe appearance which the wood should finally assume. This is due to thepresence of the zinc white in the drying oil, which though very thin andnon-lasting as a paintis sufficient at first to mask the disagreeableappearances otherwise unavoidable, and yet to yield to wear and tear,&c., simultane-- ously,or nearly so, with the completion of the realchange of surface, The mechanical and detergent action of the rain andwind, will soon remove the solid residues upon shingle roofs and likestructures treated in this way, after the chemical changes have beenaccomplished. But when the process is otherwise ended mechanical rubbingor brushing may of course be resorted to to expedite the final result.

Having thus described my invention 1 wish it to be understood that I donot confine myself to the precise ingredients employed, or to the mannerof applying the same, so long as the principles underlying my inventionare maintained. It is possible for instance, to substitute otherbleaching material in Whole or in part for the chloride of lime. Thiswould at once be accomplished by adding carbonate of soda in suitablequantity to the suspended chlorinated lime, which would cause theformation of sodium hypochlorite and calcium carbonate in quantitiesproportionate to the quantityof soda employed. Or a solution ofsodium'hypochlorite may be used at once in conjunction with theotheringredients. But I have found the chlorinated lime better adaptedfor my purpose inasmuch as it gives upon the shingles or other surface acoating or layer having some quantity, which is not readily washed away(especially when helped to resist rain by the presence of the linseed orother drying oil) and which is gradually decomposed, setting free thehypochlorous acid (or chlorine) to act upon the yellow or brownishcoloring matter of the wood, and

destroy it in conjunction with the sunlight and rain.

In place of creosote oil other antiseptics may be substituted, and forthe zinc white other white colors, though the lightness of the zinc isone of several advantages that it possesses, as it does not settle outof the paint.

The quantities hereinbefore given I have found to be the best adaptedfor general use, bnttheymay be modifiedto suitcircumstances and thequantity of water may be somewhat increased or diminished, so as to giverise to a greater or less thickness of coating on the surface to bebleached and preserved, or to facilitate transportation of themanufactured composition.

In this specification, when the word long or prolonged is used withreference to the time required to complete my process, I wish it to beunderstood that a time is meant very much in excess of that necessaryfor ordinary bleaching purposes, usually extending to months; and, bythe word detergent, as applied to coated, exposed and bleached surfaces,I refer to the cleansing power of the elements, chiefly of the rain andsnow, which remove the products of chemical action as well as theremains of the bleaching paint itself.

What I claim is- 1. A composition for bleaching and preserving woodconsisting of chlorinated lime, creosote oil and water in about theproportions specified; substantially as described.

2. A composition for bleaching and preserving wood consisting ofchlorinated lime, creosote oil, zinc white, linseed oil and water inabout the quantities specified; substantially as described.

SAM. CABOT.

